High strength suture material

ABSTRACT

A high strength abrasion resistant surgical suture material with improved tie down characteristics. The suture features a multifilament cover formed of braided strands of ultra high molecular weight long chain polyethylene and polyester. The cover surrounds a core formed of twisted strands of ultrahigh molecular weight polyethylene. The suture, provided in a #2 size, has the strength of #5 Ethibond, is ideally suited for most orthopedic procedures, and can be attached to a suture anchor or a curved needle.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to high strength surgical suturematerials, and more particularly to braided suture blends of ultrahighmolecular weight polyethylene and polyester having high strength andexcellent tie down characteristics.

[0003] 2. Description of the Related Art

[0004] Suture strength is an important consideration in any surgicalsuture material. One of the strongest materials currently formed intoelongated strands is an ultrahigh molecular long chain weightpolyethylene, typically used for fishing line and the like, which issold under the trade names Dyneema or Spectra. However, this material,while much stronger than ordinary surgical suture, does not haveacceptable knot tie down characteristics for use in surgicalapplications.

SUMMARY OF THE INVENTION

[0005] The present invention advantageously provides a high strengthsurgical suture material with improved tie down characteristics. Thesuture features a braided cover made of a blend of ultrahigh molecularweight long chain polyethylene and polyester. The polyethylene providesstrength. The polyester provides improved tie down properties.

[0006] The preferred suture includes a multifilament cover formed of aplurality of fibers of ultrahigh molecular weight polyethylene braidedwith fibers of polyester. The cover surrounds a core of twisted fibersof ultrahigh molecular weight polyethylene.

[0007] Preferably, the ultrahigh molecular weight polyethylene includesabout 60% of the cover fibers, with polyester making up about 40% of thecover filaments. The core comprises about 30% of the suture, the covermaking up about 70%. As an enhancement, the suture is provided with acoating on the cover, as is known in the prior art. The suture can bepackaged ready for use attached to a suture anchor.

[0008] Ultrahigh molecular weight polyethylene fibers suitable for usein the present invention are marketed under the Dyneema trademark byToyo Boseki Kabushiki Kaisha.

[0009] The suture of the present invention advantageously has thestrength of Ethibond #5 suture, yet has the diameter, feel and tieability of #2 suture. As a result, the suture of the present inventionis ideal for most orthopedic procedures such as rotator cuff repair,archilles tendon repair, patellar tendon repair, ACL/PCL reconstruction,hip and shoulder reconstruction procedures, and replacement for suturein anchors.

[0010] Other features and advantages of the present invention willbecome apparent from the following description of the invention whichrefers to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING(S)

[0011]FIG. 1 is a copy of a scanning electron micrograph of a length ofsuture according to the present invention.

[0012]FIG. 2 is a schematic cross section of a length of sutureaccording to the present invention.

[0013]FIG. 3 is an illustration of the suture of the present inventionattached to a suture anchor.

[0014]FIGS. 4A and 4B show the suture of the present invention attachedto a half round, tapered needle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Referring to FIG. 1, a scanning electron micrograph of a lengthof suture 2 according to the present invention is shown. Suture 2 ismade up of a cover 4 and a core 6 surrounded by the cover. See FIG. 2.Strands of ultrahigh molecular weight polyethylene (UHMWPE) 8, soldunder the tradename Dyneema or Spectra, and strands of polyester 10 arebraided together to form the cover 4. The core is formed of twistedUHMWPE.

[0016] Details of the present invention will be described further belowin connection with the following examples:

EXAMPLE 1 USP Size 5 (EP size 7)

[0017] Made on a 16 carrier Hobourns machine, the yarns used in thebraided cover are polyester type 712 and Dyneema SK65. The cover isformed using eight carriers with one end of 190 d'tex polyester percarrier, and eight carriers with one end of 220 d'tex Dyneema percarrier. The core is formed of Dyneema using one end of 440/1/3 twisted10 tpi “z” and 7 tpi “s” (core is not steam set). Picks per inch(PPI)=36. In forming the suture, the percent cover is 71.31, while thepercent of the core is 28.69. Runnage is 1991 meters per kilo.

[0018] Of the overall suture, the polyester in the cover (8 carriers×190d'tex=1520 d'tex) makes up 33.04% of the suture, and the Dyneema in thecover (8 carriers×220 d'tex=1760 dtex) makes up 38.76% of the suture.The Dyneema core (3 carriers×440 d'tex=1320 d'tex) is 28.69% of thesuture.

EXAMPLE 2 USP Size 2

[0019] The suture is 38.09% polyester, 61.91% UHMWPE, or about 40%polyester and about 60% UHMWPE.

[0020] The examples above are for size 2 and size 5 sutures. In themaking of various sizes of the inventive suture, different decitexvalues and different PPI settings can be used to achieve the requiredsize and strength needed. In addition, smaller sizes may requiremanufacture on 12 carrier machines, for example. The very smallest sizesare made without a core. Overall, the suture may range from 5% to 90%ultrahigh molecular weight polymer (Dyneema), with the balance formed ofpolyester.

[0021] The suture is preferably coated with a silicon based coating tofill in voids and provide optimum run down.

[0022] The Dyneema component of the present invention provides strength,and the polyester component is provided to improve tie ability and tiedown characteristics. However, it has been found that the Dyneemaprovides an unexpected advantage of acting as a cushion for thepolyester fibers, which are relatively hard and tend to damage eachother. The Dyneema prevents breakage by reducing damage to the polyesterwhen the suture is subjected to stress.

[0023] According to an alternative embodiment of the present invention,a partially bioabsorbable suture is provided by blending a high strengthmaterial, such as UHMWPE fibers, with a bioabsorbable material, such asPLLA or one of the other polylactides, for example. Accordingly, asuture made with about 10% Dyneema blended with absorbable fibers wouldprovide greater strength than existing bioabsorbable suture with lessstretch. Over time, 90% or more of the suture would absorb, leaving onlya very small remnant of the knot.

[0024] In one method of using the suture of the present invention, thesuture 2 is attached to a suture anchor 14 as shown in FIG. 3(prepackaged sterile with an inserter 16), or is attached to a halfround, tapered needle 18 as shown in FIGS. 4A and 4B.

[0025] Although the present invention has been described in relation toparticular embodiments thereof, many other variations and modificationsand other uses will become apparent to those skilled in the art. It ispreferred, therefore, that the present invention be limited not by thespecific disclosure herein, but only by the appended claims.

What is claimed is:
 1. A suture filament suitable for use as a suture orligature comprising a plurality of braided fibers of ultrahigh molecularweight polyethylene and polyester.
 2. The suture filament of claim 1,wherein the ultrahigh molecular weight polyethylene comprises about 60%of the braided fibers.
 3. The suture filament of claim 1, wherein thepolyester comprises about 40% of the braided filaments.
 4. The suturefilament of claim 1, further comprising a core of twisted fibers ofultrahigh molecular weight polyethylene surrounded by a cover comprisingthe plurality of braided fibers of ultrahigh molecular weightpolyethylene and polyester.
 5. The suture filament of claim 4, whereinthe core comprises about 30% of the filament.
 6. The suture filament ofclaim 4, wherein the cover comprises about 70% of the filament.
 7. Thesuture filament of claim 1, further comprising a coating disposed on thecover.
 8. A suture assembly comprising: a suture having a multifilamentcover formed of a plurality of braided fibers of ultrahigh molecularweight polyethylene and fibers of polyester, and a core formed oftwisted fibers of ultrahigh molecular weight polyethylene; and a sutureanchor attached to the suture.
 9. A suture assembly comprising: a suturehaving a multifilament cover formed of a plurality of braided fibers ofultrahigh molecular weight polyethylene and fibers of polyester, and acore formed of twisted fibers of ultrahigh molecular weightpolyethylene; and a half round, tapered needle attached to the suture.